Feasibility Study of Vermi-filtration for the Treatment of Dairy Wastewater

The wastewater generated in dairy industry contains very high organic loading and total solids and is mostly treated in ETP (Effluent Treatment Plant ), where the sludge is formed increasing the expenditure for processing and disposal along with the operation cost. Earthworms body act as a ‘biofilter’ and they were found to increase the removal efficiency of BOD3 – 89.3 %, 86.5 %, 91.6 %, COD – 81.6 %, 80.3 % ,85.4 %, TS – 82.3 %,73.9 %, 85.5 %, TDS 85.6 %, 82.9 %, 87.1 % and OIL and GREASE content by 97.2 %, 97.2 %, 99 % for single earthworm species of reactor 1 and reactor 3 and mixed earthworm species for reactor 2 using black cotton soil for about 98 days and for varied bed depths using garden soil of 10 cm, 15 cm and 20 cm for mixed earthworm species of reactor 1, reactor 2 and reactor 3 for about 40 days were found to be of BOD3 – 78.45 %, 68.35 %, 54.52 %, COD – 55.56 %, 46.42 %, 23.37 %, TS – 55.32 %, 42.02 %, 23.37 %, TDS – 60.67 %, 50.15 %, 25.38 % and OIL and GREASE – 29.9 %, 16.82 %, 9.34 % . The height of vermibed is considered as an important factor in vermi-filtration method. Earthworm treat the wastewater by the mechanism in the process include: ‘feeding’ and ‘biodegradation. Also increase the hydraulic conductivity and natural aeration by grinding the soil particle. In the present study three vermi-filters and one nonvermi filter was designed. The effluent passed through top layer of the filter and found out the removal efficiency of physicochemical parameter. The suspended solids trapped on top of the vermi-filter and processed by earthworms. There is no sludge formation in this process which requires additional expenditure on landfill and disposal. The process is odour free, ecofriendly and cost effective. The final vermi-filtered water was clean enough to be used for irrigation, in parks and garden.